Developing an efficient gas sensor device with high sensitivity and selectivity still remains a challenge for its practical application. Herein, we demonstrated a facile one-step hydrothermal method to deposit cocoon-like ZnO nanoparticles onto surfaces of graphene sheets, leading to the formation of ZnO/graphene composite. The structural characterization confirmed the successful deposition of ZnO nanocrystals with hexagonal wurtzite on graphene sheets, which further facilitated the exfoliation of graphene sheets. The gas sensing performances of as-prepared ZnO/graphene composites were investigated towards a series of typical organic vapors. The results showed that the ZnO/graphene composite exhibited significantly higher performance than that of pure ZnO nanoparticles. Especially, the ZnO/graphene could offer a high gas response value of 513 towards 1000 ppm of ethanol, which is nearly 5.0 times higher than that of pure ZnO, indicating the potential application as a sensor material towards enhanced gas detection. (C) 2015 Elsevier B.V. All rights reserved.